I'm not sure if this is at all helpful to you or others but I have a 325P2 and had no luck using ARC XT software to add Trinity DMR Tier 3 frequencies to my scanner. On a whim, I added the frequencies from the RR database manually and now the scanner picks up all the Trinity talkgroups well. I chose the Wolcott transmitter site as it is closer to my home. Several talkgroups are very active during the day. I know nothing about programming the SDS 100 but if there is a manual way to program it, that might be worth a try.
Jim